It is known to provide a wide angle rearward field of view to a driver of a vehicle via a wide angle reflective element at one or both of the exterior rearview mirror assemblies. Such a wide angle rearward field of view may be provided via a curved mirror reflector, or an auxiliary wide angle reflective element may be provided at a portion of a generally planar mirror reflector, such as via a curved auxiliary reflector element adhered to the generally planar mirror reflector. Such add-on curved auxiliary reflectors may be provided at the front surface or first surface (the surface of the mirror reflector that is generally facing rearward and at least partially toward the driver of the vehicle) and provide a reduced image size (as compared to the size of the generally planar reflector) wide angle rearward field of view that is readily viewable by the driver of the vehicle. Other auxiliary wide angle reflectors have been proposed, such as those described in U.S. Pat. Nos. 7,255,451; 7,195,381; 6,717,712; 7,126,456; 6,315,419; 7,097,312; 6,522,451; 6,315,419; 5,080,492; 5,050,977; and/or 5,033,835, which are hereby incorporated herein by reference in their entireties.
Typically, the process for adhering an auxiliary wide angle element to a reflective element of an exterior rear view mirror has been with use of a liquid adhesive. The process typically starts with dispensing a known volume of liquid adhesive on the mirror surface and the auxiliary wide angle element is then lowered very slowly on top of the adhesive. In order to not capture bubbles or to reduce the bubbles between the auxiliary wide angle element and the mirror reflective element, it is important to properly lower the auxiliary wide angle element on top of the liquid adhesive. This is typically done with a hinged motion where the auxiliary wide angle element makes contact on one side and then gradually is lowered on the opposite side. Since spacer beads are not used in such an application, the viscosity of the fluid must be selected such that when the robot lowers the auxiliary wide angle element to a pre-determined height, there is only a small amount of squeeze out. Also, if the adhesive viscosity is too low, the bond gap may not be maintained as the weight of the auxiliary wide angle element may compress the adhesive.
Other ways of laminating the auxiliary wide angle element to the mirror may use clear laminating tapes or PVB which would require an autoclave lamination process. Such an autoclave lamination process can be used for non-electrochromic applications, but for electrochromic applications, the auxiliary wide angle element would have to be attached to the glass substrate just after the conductive layer deposition and before dispensing the perimeter seal. This is because a finished electrochromic mirror reflective element will not survive the autoclave lamination which is typically at about 130 to 200 psi of pressure and at about 150 degrees Celsius.